Combined gas turbine

ABSTRACT

A gas turbine arrangement for ships in which a low temperature turbine using low grade fuel is mounted above the deck and is directly coupled to a compressor for a second turbine mounted in the engine room which operates at high temperature and with high quality fuel. The entire output of the second turbine drives the ship propeller, preferably through reduction gearing. The compressed air from the above-deck turbine may be heated by the exhaust gases from the below-deck turbine. The above-deck turbine may be a two-stage arrangement having an intercooler between the two stages of compression. Additionally a bleeder system and heat exchanger may be incorporated in the output of the first compressor.

United States Patent 1 1 Tamaru et al.

[ COMBINED GAS TURBINE [75] Inventors: Shigeo Tamara; Kiyomi Teshima,

both of Okayama, Japan [73] Assignee: Mitsu Shipbuilding and EngineeringCo. Ltd., Tokyo, Japan [22] Filed: July 22, 1971 [211 Appl. No.: 165,130

[30] Foreign Application Priority Data 6/1956 Barrett et al 60/39.l53/1965 Schell et a]. 60/221 [5 7] ABSTRACT A gas turbine arrangement forships in which a low temperature turbine using low grade fuel is mountedabove the deck and is directly coupled to a compressor for a secondturbine mounted in the engine room which operates at high temperatureand with high quality fuel. The entire output of the second turbinedrives the ship propeller, preferably through reduction gearing. Thecompressed air from the above-deck turbine may be heated by the exhaustgases from the below-deck turbine. The above deck turbine may be atwo-stage arrangement having an intercooler between the two stages ofcompression. Additionally a bleeder system and heat exchanger may beincorporated in the output of the first compressor.

5 Claims, 9 Drawing Figures PATENTEU 3,749,047

sum 2 or 3 FIG; M B2 is that suction air volume of the 1 COMBINED GASTURBINE The present invention relates bine effectively used for ship.

The gas turbine is light in weight and small in size but large inoutput, and thereby widely used for aircraft. However application of gasturbine to ship is extremely limited and only found specifically innaval craft. The reason for this is that the use of low grade fuel isdifficult because of increase of fuelexpense. Further reason gas turbineper output of exhaust gas generto a combined gas turis large, thereby alarge amount ated and a large sectional area of exhaust ducts requiredin spite of the fact that the gas turbine engine itself is small in.size. These factors are of course. disadvantageous to apply the gasturbine to ships.

The present invention has for its object to remove the above mentioneddisadvantages, and is characterized in that two or more gas turbines arecombined to form a composite cycle, so that. amount of suction airintroduced in the output turbine isdecreased, and thereby decreasingcross-sectional area of the suction and the exhaust ducts thereof.

The combined gas turbine in accordance with the present inventionare.such composed that an air compressor is driven by. means of anindependent gas turbine which consumes chiefly low grade fuel such asBunker C heavy oil or Heavy Marine Fuel Oil and high pressure airdischarged from the compressor is introduced into combustor of outputturbine and then the produced hightemperature and high pressure gas isintroducedintothe output turbine to obtain output.

In the drawings:

FIGS. 1a and lb are schematic diagrams showing conventional gasturbines;

FIG. 2 is a schematic diagram showing the present invention;

FIG. 3 is a schematic diagram showing a case in which the presentinvention is applied to ships; and

FIGS. 4 through.8 are schematic diagrams showing other embodiments ofthe present invention applied to ships respectively.

Referring to the drawings, in accordance with the present inventionordinary gas turbinesA and B shown in FIGS. and lb are combined tocompose one unit as shown in FIG. 2. The combined gas turbine comprises,a compressor side C and an output side D. The compressor side comprisesa compressor C combustor 8,, output turbine T, and compressor C,connected to the output shaft of the turbine T The high pressure air.discharged from the compressor C, is introduced in the combustor B, ofthe output side turbine'to drive the turbine T In this case, when theoutput of turbine is represented by W, ant the requiredpower forcompressor isW the following equation must be held:

From this relation, it will be seen by simple calculation that the poweroutput HP; isequal to the sum of output HP ofthe gas turbine A andoutput HP; of the gas turbine B. That is to say, with respect to theoutput, the present invention does not show a profit in particular.However, theeconomy of fuel cost and the reduction of space for thesuction and the exhaust ducts for installing the turbine in the ship aregreatlyaffected by the present invention. The reasone will be describedhereinafter. The output of the gas turbine increases with thetemperature of gas in the combustor B thereof. If low grade fuel such asBunker C heavy oil or Heavy Marine Fuel Oil is used, ash is generated,and turbine blades are corroded at high temperature. Therefore, gastemperature is at present considered not to exceed 750C. In the combinedgas turbine according to the present invention, .flow rate of airintroduced into the combustor B, by means of the compressor C, is abouttwo point three times as much as that of the combustor 8,. This meansthat fuel consumption ratio of the combustor B, is about percent ofwhole fuel consumption of the conbined turbine. The present inventioncan provide an economical combined turbine by using a low grade fuel inthe combustor B of large fuel consumption ratio, even if the fuelconsumption rate per output is increased owing to low gas temperaturebelow 750C. While, high quality fuel such as light oil is used in thecombustor 8,, high power output is obtained by raising the gastemperature.

Consideration is now given to amount of air necessary for obtaining arequired power output HP In the conventional single turbine, abouttwo-thirds of output of the turbine is alloted for driving thecompressor and about one-thirds of the output is available for use. Thissituation prevails also in the turbine of the present application. Theturbine T of the present invention need not drive the compressor andsufiices to generate about one-thirds of power output comparing with theconventional turbine having the same output HP which means that theamount of air to be supplied to the combus'tor B decreases to aboutone-thirds of conventional case. Accordingly, the cross-sectional areaof the duct leading to the combustor B, also becomes smaller.

The above rough calculation is based on an assumption that thecombustors B and B are equal in temperature. However, the temperature ofthe combustor B is elevated higher than that of the combustor BAccordingly, the ratio of the required air volume is slightly differentfrom the above value.

Explanation will be made about another embodiment, shown in FIG. 3, ofthe present invention. As shown in the drawing, the compressor side Cshown in FIG. 2 is located above the deck and the output side D isarranged in the engine room and connected through the reduction gear R6to the propeller. It is to be commented that GT (I) shown in the drawingrepresents the turbine of the compressor side in block.

By employing such arrangement, the duct system in the hull is enough toprovide a duct for air to be supplied to the combustor B: only and theamount of air is only about one-thirds of the total required air asmentioned above. In addition, the air flowing into the combustor B: hasbeen compressed by the compressor C below one-fifth or less of theinitial volume, consequently, the cross-sectional area of the ductrequired for necessary output is reduced to one-tenth or less ascompared with conventional systems.

The efficiency of the turbine may be improved by employing various knownmeans such as preheating by e'xaust gas, two-stage compression, intercooling, bleeder system, etc. as shown in FIGS. 4 through 8. The symbolsGT (II), HE and IC shown in the drawings indicate a turbine, heatexchanger and inter coller respectively.

As will be obvious in the preceding description, according to thepresent invention, the economy of fuel cost is improved as a whole byusing low grade fuel in the large ratio to whole fuel consumption, aswell as the cross-sectional area of the air suction and exhaust ductscan be remarkably reduced. Besides, since the gas turbine consuming lowgrade fuel is located above the deck, maintenance of the gas turbine iseasy.

What is claimed is:

l. A combined gas turbine drive for a ship having a hull closed at thetop by a deck, a propeller for driving the ship having a propeller shaftextending longitudinally through the bottom of the hull, and an engineroom in the bottom of the hull below said deck for housing the controlsof the ship for driving the propeller, said drive for the shipcomprising a first gas turbine, a combustor utilizing compressed air andfuel to generate the gas for driving said first turbine, means mountingsaid first turbine and combustor above the deck of said ship, a secondturbine having an output shaft coupled to said propeller shaft, meansmounting said second turbine below the deck of said ship in said engineroom, a combustor for feeding combustion gases to said second turbine,means to supply a different fuel and compressed air to said combustor,said combustion burning said fuel and generating said combustion gases,a compressor for supplying compressed air to said second combustor,means mounting said compressor on the deck or above the deck of theship, means coupling the drive shaft of said first turbine to saidsecond compressor whereby said compressor is driven by said firstturbine, and high pressure air lines extending from the compressor abovethe deck of the ship to the combustor for the second turbine.

2. A combined gas turbine drive according to claim 1 wherein saidcombustor for supplying gas to said second turbine is operative at hightemperature and with high quality fuel and said combustor for supplyinggas to said first turbine is operative with low grade fuel such asBunker C heavy oil or Heavy Marine Fuel Oil.

3. A combined gas turbine drive for ships according to claim 1 includingmeans to couple the entire output of said second turbine to the shippropeller.

4. A drive according to claim 3 wherein said coupling means consists ofreduction gearing.

5. A drive for ships according to claim 1 including a heat exchanger toreceive exhaust gases from the second turbine, and means to directcompressed air from said compressor through said heat exchanger prior topassing into said combustor.

1. A combined gas turbine drive for a ship having a hull closed at thetop by a deck, a propeller for driving the ship having a propeller shaftextending longitudinally through the bottom of the hull, and an engineroom in the bottom of the hull below said deck for housing the controlsof the ship for driving the propeller, said drive for the shipcomprising a first gas turbine, a combustor utilizing compressed air andfuel to generate the gas for driving said first turbine, means mountingsaid first turbine and combustor above the deck of said ship, a secondturbine having an output shaft coupled to said propeller shaft, meansmounting said second turbine below the deck of said ship in said engineroom, a combustor for feeding combustion gases to said second turbine,means to supply a different fuel and compressed air to said combustor,said combustion burning said fuel and generating said combustion gases,a compressor for supplying compressed air to said second combustor,means mounting said compressor on the deck or above the deck of theship, means coupling the drive shaft of said first turbine to saidsecond compressor whereby said compressor is driven by said firstturbine, and high pressure air lines extending from the compressor abovethe deck of the ship to the combustor for the second turbine.
 2. Acombined gas turbine drive according to claim 1 wherein said combustorfor supplying gas to said second turbine is operative at hightemperature and with high quality fuel and said combustor for supplyinggas to said first turbine is operative with low grade fuel such asBunker C heavy oil or Heavy Marine Fuel Oil.
 3. A combined gas turbinedrive for ships according to claim 1 including means to couple theentire output of said second turbine to the ship propeller.
 4. A driveaccording to claim 3 wherein said coupling means consists of reductiongearing.
 5. A drive for ships according to claim 1 including a heatexchanger to receive exhaust gases from the second turbine, and means todirect compressed air from said compressor through said heat exchangerprior to passing into said combustor.